Looked around and nobody knows maybe handed down from older models Luxury Touring, LS Luxury Sport? LS is a base model like mine with a few options. LT , LTZ have options and higher trim levels that are standard. LS1 engines ,Maybe a secret company code hush! hush!

From the GM website I understand it to be a trim level designation.
In the trucks they really dont make a standard, thats the LS, then LT is a 1 upgrade, and LTZ is a 2 upgrade.
Certain options can be added depending on the trim level, not all options are available with all trim levels.